RHAYNCHITIDA—ISOTHEIN AA—ISOTHEINI. rie 
remarkable form found at Oeningen, for which Heer has proposed the name 
Antliarhinus, on account of the rostrum “of a hair-like fineness.” 
The occurrence of other Rhynchophora, which must plainly belong to 
the Rhynchitidee, but which share with Pterocolus some characteristics other- 
wise peculiar to it, is distinct evidence that Le Conte was correct in sepa- 
rating Pterocolus from the genera with which it had been formerly asso- 
ciated and placing it in the Rhynchitide. 
There appear to be two groups of genera belonging to this subfamily, 
which provisionally may be regarded as tribes. They may be separated as 
follows : 
Table of the tribes of Isotheine. 
Large species normally of an elongated form with straight dorsum, the head generally 
of considerable length and the rostrum always rigidly straight ......... Isotheini. 
Small species normally of a plump and compact form, with well-rounded dorsum, the 
head shorter.the rostrum either straight or gently curved ....... Toxorhynchini. 
iribemi > Om EmN 
The members of this tribe are peculiar for their considerable size, the 
elongate, more or less parallel-sided form, there being scarcely any if any 
diminution in breadth forward before the middle of the prothorax; some- 
times, however, they are stout, but then do not have so arched a body as 
in the suczeeding tribe; the head is usually of exceptional length, and the 
rostrum always rigidly straight and porrect, and usually long and slender. 
Table of the genera of Isotheini. 
Body elongate, fully two and a half times longer than broad or high; rostrum directed 
nearly straight forward; joints of club of antenne larger at apex than at 
base. 
Ninth and tenth antennal joints only a little larger at apex than at base. Third 
ventral segment of abdomen as long as the second........... Paltorhynchus. 
Ninth and tenth antennal joints twice as broad at apex as at base. Third veutral 
segment of abdomen shorter than the second ...................-... Tsothea. 
Body stouter, but little more than twice as long as broad or high; rostrum more or less 
declivent; joints of antennal club not enlarged apically... . Trypanorhynchus, 
2 
MON XXI 
